Lithographic apparatus and device manufacturing method

ABSTRACT

To facilitate, for example, removal of a substrate between exposures of different substrates, an actuated closing plate is used to replace a substrate, a substrate table, or both, as a part of a boundary of a space in a lithographic apparatus containing liquid without, for example, breaking a seal containing the liquid.

FIELD

The present invention relates to a lithographic apparatus and a methodfor manufacturing a device.

BACKGROUND

A lithographic apparatus is a machine that applies a desired patternonto a substrate, usually onto a target portion of the substrate. Alithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In that instance, a patterning device, whichis alternatively referred to as a mask or a reticle, may be used togenerate a circuit pattern to be formed on an individual layer of theIC. This pattern can be transferred onto a target portion (e.g.comprising part of, one, or several dies) on a substrate (e.g. a siliconwafer). Transfer of the pattern is typically via imaging onto a layer ofradiation-sensitive material (resist) provided on the substrate. Ingeneral, a single substrate will contain a network of adjacent targetportions that are successively patterned. Known lithographic apparatusinclude so-called steppers, in which each target portion is irradiatedby exposing an entire pattern onto the target portion at one time, andso-called scanners, in which each target portion is irradiated byscanning the pattern through a radiation beam in a given direction (the“scanning”-direction) while synchronously scanning the substrateparallel or anti-parallel to this direction. It is also possible totransfer the pattern from the patterning device to the substrate byimprinting the pattern onto the substrate.

It has been proposed to immerse the substrate in the lithographicprojection apparatus in a liquid having a relatively high refractiveindex, e.g. water, so as to fill a space between the final element ofthe projection system and the substrate. The point of this is to enableimaging of smaller features since the exposure radiation will have ashorter wavelength in the liquid. (The effect of the liquid may also beregarded as increasing the effective NA of the system and alsoincreasing the depth of focus.) Other immersion liquids have beenproposed, including water with solid particles (e.g. quartz) suspendedtherein.

However, submersing the substrate or substrate and substrate table in abath of liquid (see, for example, U.S. Pat. 4,509,852, herebyincorporated in its entirety by reference) means that there is a largebody of liquid that must be accelerated during a scanning exposure. Thisrequires additional or more powerful motors and turbulence in the liquidmay lead to undesirable and unpredictable effects.

One of the solutions proposed is for a liquid supply system to provideliquid on only a localized area of the substrate and in between thefinal element of the projection system and the substrate (the substrategenerally has a larger surface area than the final element of theprojection system). One way which has been proposed to arrange for thisis disclosed in PCT patent application WO 99/49504, hereby incorporatedin its entirety by reference. As illustrated in FIGS. 2 and 3, liquid issupplied by at least one inlet IN onto the substrate, preferably alongthe direction of movement of the substrate relative to the finalelement, and is removed by at least one outlet OUT after having passedunder the projection system. That is, as the substrate is scannedbeneath the element in a −X direction, liquid is supplied at the +X sideof the element and taken up at the −X side. FIG. 2 shows the arrangementschematically in which liquid is supplied via inlet IN and is taken upon the other side of the element by outlet OUT which is connected to alow pressure source. In the illustration of FIG. 2 the liquid issupplied along the direction of movement of the substrate relative tothe final element, though this does not need to be the case. Variousorientations and numbers of in- and out-lets positioned around the finalelement are possible, one example is illustrated in FIG. 3 in which foursets of an inlet with an outlet on either side are provided in a regularpattern around the final element.

In an immersion lithography technique, a space between the projectionsystem and the substrate is filled with a liquid (such as water). Duringexposure of the substrate, the substrate forms part of a boundary whichcontains the liquid. During removal of that substrate and replacementwith another substrate, for example, the liquid may be drained from thespace to allow for the substrate change. A possible downside to thisapproach is that drying spots may be formed on an element of theprojection system in contact with the liquid. Additionally oralternatively, changes in the liquid and vacuum flow to remove theliquid may take time to settle, possibly leading to loss in throughput.

SUMMARY

Accordingly, it would be advantageous, for example, to keep an elementof an immersion lithography apparatus projection system immersed duringa removal of a substrate by swapping a closing plate for the substratewithout disturbing the liquid which is present between the substrate andthe optical element. By using another body (e.g., a closing plate) thatfulfills the function of providing a boundary that contains the liquid,it may not be necessary to remove the liquid from between the substrateand the projection system during removal of the substrate (and supply ofa new substrate).

According to an aspect of the invention, there is provided alithographic projection apparatus, comprising:

a substrate table configured to hold a substrate;

a projection system configured to project a patterned beam of radiationonto the substrate;

a liquid confinement structure configured to confine a liquid in a spacebetween the projection system and the substrate, the substrate, thesubstrate table, or both, configured to form a part of a boundary of thespace; and

a closing plate configured to form a part of a boundary of the space inplace of the substrate, the substrate table, or both, when moved withoutsubstantially disturbing the liquid, the liquid confinement structure,or both.

According to a further aspect of the invention, there is provided adevice manufacturing method, comprising:

providing a liquid to a space through which a patterned beam passes, asubstrate, a substrate table, or both, forming a part of a boundary ofthe space;

sealing the liquid to the space, the seal acting between the substrate,a substrate table, or both, and another structure;

replacing the substrate, the substrate table, or both, with a closingplate as the part of the boundary of the space without breaking theseal; and

projecting a patterned beam of radiation through the liquid onto thesubstrate.

According to another aspect of the invention, there is provided alithographic projection apparatus, comprising:

a substrate table configured to hold a substrate;

a projection system configured to project a patterned beam of radiationonto the substrate;

a liquid confinement structure configured to confine a liquid in a spacebetween the projection system and the substrate, the substrate, thesubstrate table, or both, configured to form a part of a boundary of thespace;

a closing plate displaced in a horizontal plane from the substrate tableand configured to form a part of a boundary of the space in place of thesubstrate, the substrate table, or both; and

an actuator configured to move the closing plate in the horizontalplane.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts a lithographic apparatus according to an embodiment ofthe invention;

FIGS. 2 and 3 depict a liquid supply system for use in a lithographicprojection apparatus;

FIG. 4 depicts a further liquid supply system for use in a lithographicprojection apparatus;

FIG. 5 depicts a close up view of another liquid supply system accordingto an embodiment of the present invention;

FIGS. 6 a and 6 b show a first step in the method according to anembodiment of the present invention;

FIGS. 7 a and 7 b show a second step in the method according to anembodiment of the present invention;

FIGS. 8 a and 8 b show a third step in the method according to anembodiment of the present invention; and

FIGS. 9 a and 9 b show a fourth step in the method according to anembodiment of the present invention.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a lithographic apparatus according to oneembodiment of the invention. The apparatus comprises:

an illumination system (illuminator) IL configured to condition aradiation beam PB (e.g. UV radiation or DUV radiation).

a support structure (e.g. a mask table) MT constructed to hold apatterning device (e.g. a mask) MA and connected to a first positionerPM configured to accurately position the patterning device in accordancewith certain parameters;

a substrate table (e.g. a wafer table) WT constructed to hold asubstrate (e.g. a resist-coated wafer) W and connected to a secondpositioner PW configured to accurately position the substrate inaccordance with certain parameters; and

a projection system (e.g. a refractive projection lens system) PLconfigured to project a pattern imparted to the radiation beam PB bypatterning device MA onto a target portion C (e.g. comprising one ormore dies) of the substrate W.

The illumination system may include various types of optical components,such as refractive, reflective, magnetic, electromagnetic, electrostaticor other types of optical components, or any combination thereof, fordirecting, shaping, or controlling radiation.

The support structure holds the patterning device in a manner thatdepends on the orientation of the patterning device, the design of thelithographic apparatus, and other conditions, such as for examplewhether or not the patterning device is held in a vacuum environment.The support structure can use mechanical, vacuum, electrostatic or otherclamping techniques to hold the patterning device. The support structuremay be a frame or a table, for example, which may be fixed or movable asrequired. The support structure may ensure that the patterning device isat a desired position, for example with respect to the projectionsystem. Any use of the terms “reticle” or “mask” herein may beconsidered synonymous with the more general term “patterning device.”

The term “patterning device” used herein should be broadly interpretedas referring to any device that can be used to impart a radiation beamwith a pattern in its cross-section such as to create a pattern in atarget portion of the substrate. It should be noted that the patternimparted to the radiation beam may not exactly correspond to the desiredpattern in the target portion of the substrate, for example if thepattern includes phase-shifting features or so called assist features.Generally, the pattern imparted to the radiation beam will correspond toa particular functional layer in a device being created in the targetportion, such as an integrated circuit.

The patterning device may be transmissive or reflective. Examples ofpatterning devices include masks, programmable mirror arrays, andprogrammable LCD panels. Masks are well known in lithography, andinclude mask types such as binary, alternating phase-shift, andattenuated phase-shift, as well as various hybrid mask types. An exampleof a programmable mirror array employs a matrix arrangement of smallmirrors, each of which can be individually tilted so as to reflect anincoming radiation beam in different directions. The tilted mirrorsimpart a pattern in a radiation beam which is reflected by the mirrormatrix.

The term “projection system” used herein should be broadly interpretedas encompassing any type of projection system, including refractive,reflective, catadioptric, magnetic, electromagnetic and electrostaticoptical systems, or any combination thereof, as appropriate for theexposure radiation being used, or for other factors such as the use ofan immersion liquid or the use of a vacuum. Any use of the term“projection lens” herein may be considered as synonymous with the moregeneral term “projection system”.

As here depicted, the apparatus is of a transmissive type (e.g.employing a transmissive mask). Alternatively, the apparatus may be of areflective type (e.g. employing a programmable mirror array of a type asreferred to above, or employing a reflective mask).

The lithographic apparatus may be of a type having two (dual stage) ormore substrate tables (and/or two or more mask tables). In such“multiple stage” machines the additional tables may be used in parallel,or preparatory steps may be carried out on one or more tables while oneor more other tables are being used for exposure.

Referring to FIG. 1, the illuminator IL receives a radiation beam from aradiation source SO. The source and the lithographic apparatus may beseparate entities, for example when the source is an excimer laser. Insuch cases, the source is not considered to form part of thelithographic apparatus and the radiation beam is passed from the sourceSO to the illuminator IL with the aid of a beam delivery system BDcomprising, for example, suitable directing mirrors and/or a beamexpander. In other cases the source may be an integral part of thelithographic apparatus, for example when the source is a mercury lamp.The source SO and the illuminator IL, together with the beam deliverysystem BD if required, may be referred to as a radiation system.

The illuminator IL may comprise an adjuster AD for adjusting the angularintensity distribution of the radiation beam. Generally, at least theouter and/or inner radial extent (commonly referred to as σ-outer andσ-inner, respectively) of the intensity distribution in a pupil plane ofthe illuminator can be adjusted. In addition, the illuminator IL maycomprise various other components, such as an integrator IN and acondenser CO. The illuminator may be used to condition the radiationbeam, to have a desired uniformity and intensity distribution in itscross-section.

The radiation beam PB is incident on the patterning device (e.g., maskMA), which is held on the support structure (e.g., mask table MT), andis patterned by the patterning device. Having traversed the mask MA, theradiation beam PB passes through the projection system PL, which focusesthe beam onto a target portion C of the substrate W. With the aid of thesecond positioner PW and position sensor IF (e.g. an interferometricdevice, linear encoder or capacitive sensor), the substrate table WT canbe moved accurately, e.g. so as to position different target portions Cin the path of the radiation beam PB. Similarly, the first positioner PMand another position sensor (which is not explicitly depicted in FIG. 1)can be used to accurately position the mask MA with respect to the pathof the radiation beam PB, e.g. after mechanical retrieval from a masklibrary, or during a scan. In general, movement of the mask table MT maybe realized with the aid of a long-stroke module (coarse positioning)and a short-stroke module (fine positioning), which form part of thefirst positioner PM. Similarly, movement of the substrate table WT maybe realized using a long-stroke module and a short-stroke module, whichform part of the second positioner PW. In the case of a stepper (asopposed to a scanner) the mask table MT may be connected to ashort-stroke actuator only, or may be fixed. Mask MA and substrate W maybe aligned using mask alignment marks M1, M2 and substrate alignmentmarks P1, P2. Although the substrate alignment marks as illustratedoccupy dedicated target portions, they may be located in spaces betweentarget portions (these are known as scribe-lane alignment marks).Similarly, in situations in which more than one die is provided on themask MA, the mask alignment marks may be located between the dies.

The depicted apparatus could be used in at least one of the followingmodes:

1. In step mode, the mask table MT and the substrate table WT are keptessentially stationary, while an entire pattern imparted to theradiation beam is projected onto a target portion C at one time (i.e. asingle static exposure). The substrate table WT is then shifted in the Xand/or Y direction so that a different target portion C can be exposed.In step mode, the maximum size of the exposure field limits the size ofthe target portion C imaged in a single static exposure.

2. In scan mode, the mask table MT and the substrate table WT arescanned synchronously while a pattern imparted to the radiation beam isprojected onto a target portion C (i.e. a single dynamic exposure). Thevelocity and direction of the substrate table WT relative to the masktable MT may be determined by the (de-)magnification and image reversalcharacteristics of the projection system PL. In scan mode, the maximumsize of the exposure field limits the width (in the non-scanningdirection) of the target portion in a single dynamic exposure, whereasthe length of the scanning motion determines the height (in the scanningdirection) of the target portion.

3. In another mode, the mask table MT is kept essentially stationaryholding a programmable patterning device, and the substrate table WT ismoved or scanned while a pattern imparted to the radiation beam isprojected onto a target portion C. In this mode, generally a pulsedradiation source is employed and the programmable patterning device isupdated as required after each movement of the substrate table WT or inbetween successive radiation pulses during a scan. This mode ofoperation can be readily applied to maskless lithography that utilizesprogrammable patterning device, such as a programmable mirror array of atype as referred to above.

Combinations and/or variations on the above described modes of use orentirely different modes of use may also be employed.

A further immersion lithography solution with a localized liquid supplysystem is shown in FIG. 4. Liquid is supplied by two groove inlets IN oneither side of the projection system PL and is removed by a plurality ofdiscrete outlets OUT arranged radially outwardly of the inlets IN. Theinlets IN and OUT can be arranged in a plate with a hole in its centerand through which the projection beam is projected. Liquid is suppliedby one groove inlet IN on one side of the projection system PL andremoved by a plurality of discrete outlets OUT on the other side of theprojection system PL, causing a flow of a thin film of liquid betweenthe projection system PL and the substrate W. The choice of whichcombination of inlet IN and outlets OUT to use can depend on thedirection of movement of the substrate W (the other combination of inletIN and outlets OUT being inactive).

Another immersion lithography solution with a localized liquid supplysystem solution which has been proposed is to provide the liquid supplysystem with a liquid confinement structure which extends along at leasta part of a boundary of the space between the final element of theprojection system and the substrate table. Such a solution isillustrated in FIG. 5. The liquid confinement structure is substantiallystationary relative to the projection system in the XY plane thoughthere may be some relative movement in the Z direction (in the directionof the optical axis). A seal is formed between the liquid confinementstructure and the surface of the substrate. In an embodiment, the sealis a contactless seal such as a gas seal. Such a system with a gas sealis disclosed in U.S. patent application Ser. No. 10/705,783, herebyincorporated in its entirety by reference.

Referring to FIG. 5, the reservoir 10 forms a contactless seal to thesubstrate around the image field of the projection system so that liquidis confined to fill a space between the substrate surface and the finalelement of the projection system. The reservoir is formed by a liquidconfinement structure 12 positioned below and surrounding the finalelement of the projection system PL. Liquid is brought into the spacebelow the projection system and within the liquid confinement structure12. The liquid confinement structure 12 extends a little above the finalelement of the projection system and the liquid level rises above thefinal element so that a buffer of liquid is provided. The liquidconfinement structure 12 has an inner periphery that at the upper endpreferably closely conforms to the shape of the projection system or thefinal element thereof and may, e.g., be round. At the bottom, the innerperiphery closely conforms to the shape of the image field, e.g.,rectangular though this need not be the case.

The liquid is confined in the reservoir by a seal 16 such as a gas sealbetween the bottom of the liquid confinement structure 12 and thesurface of the substrate W. The gas seal may be formed by gas, e.g. air,synthetic air, N₂ or an inert gas, provided under pressure via inlet 15to the gap between liquid confinement structure 12 and substrate andextracted via first outlet 14. The overpressure on the gas inlet 15,vacuum level on the first outlet 14 and geometry of the gap are arrangedso that there is a high-velocity gas flow inwards that confines theliquid. It will be understood by the person skilled in the art thatother types of seal could be used to contain the liquid.

According to an embodiment of the invention, an actuated closing plate20 is provided which moves horizontally into position under theprojection system, replacing the substrate table, which moves away fromits position under the projection system horizontally. The top surfaceof the actuated closing plate 20 is positioned at a substantially equalheight to the substrate table such that continuous, undisturbed motionis allowed when the substrate table is moved away from its positionunder the projection system, while the seal containing the liquid in theliquid confinement structure is maintained. Part of one or morelong-stroke actuators which are used to move the substrate table mayalso be used for horizontal actuation of the closing plate. As describedin more detail below, active compensation of the change in vertical loadon the substrate table, when the force associated with the liquidconfinement structure 12 is moved from the substrate table to theclosing plate, may also be employed. The actuated closing plate 20 ispositioned and/or shaped such that it does not block any interferometerbeams during measurement by these beams.

One or more advantages of supplying an actuated closing plate mayinclude a faster substrate exchange, maintenance of gas, liquid andvacuum flows in and around the liquid confinement structure at asubstantially constant level (thus possibly reducing settling times anddecreasing the likelihood of contamination), reduction of mechanicaldisturbances of the projection system and/or the substrate table,improved utilization of space on the substrate table (as no separateclosing plate need be provided on the substrate table) and eliminationof drying spots on the projection system. Additionally or alternatively,the closing plate according to an embodiment of the invention may avoidthe need to remove (and then replace) the liquid or moved the substratevertically out of position so that a closing plate may be put in itsplace. Changes in liquid, gas and vacuum flows may take time to settleand vertical movement may cause disturbances on the projection systemand on the substrate table. Turning to FIGS. 6 to 9, FIGS. 6 a, 7 a, 8 aand 9 a show plan views of the substrate table WT and actuated closingplate 20 in relation to the projection system PL. FIGS. 6 b, 7 b, 8 band 9 b show side views of the substrate table WT and actuated closingplate 20 in relation to the projection system PL.

FIGS. 6 a and 6 b show the relative positions of the substrate table WTand the actuated closing plate 20 during, for example, exposure of thesubstrate W. The closing plate is out of the way of the projectionsystem PL and the substrate W is lined up with the projection system PL.

FIGS. 7 a and 7 b show the relative positions of the substrate table WTand the actuated closing plate 20 when, for example, exposure of thesubstrate W is complete or nearly complete. The actuated closing plate20 is moved into a position such that it is aligned horizontally withthe substrate table WT and vertically with the projection system PL.

FIGS. 8 a and 8 b show the actuated closing plate 20 replacing thesubstrate table WT once, for example, the exposure of the substrate W iscomplete. Both the actuated closing plate 20 and the substrate table WTmove in the same direction, at the same horizontal level.

FIGS. 9 a and 9 b show the actuated closing plate 20 in position underthe projection system PL with the actuated closing plate 20 acting asone side of the boundary containing the liquid 11. The substrate W cannow, for example, be swapped with another substrate W on the substratetable WT and the liquid 11 has not been disturbed.

An advantage of this system is that the liquid confinement structure 12,the projection system PL, the substrate W and/or the actuated closingplate 20 is not disturbed throughout a substrate exchange procedure.Furthermore, there may be no vertical movement of the substrate table WTand/or the actuated closing plate 20 so that the risk of gas beingintroduced into the liquid supply system is reduced.

Furthermore, the substrate table WT may comprise an active compensator25 configured to compensate for a change in force when a force exertedby the liquid confinement structure is removed from it. This compensatormay comprise a vertical motion sensor and/or a pressure sensor on thesubstrate table and a control system configured to send a compensationsignal to, for example, a substrate table positioner PW, the substratetable positioner PW configured to move the substrate table WT inresponse to the signal to compensate for the change in force.Additionally or alternatively, the actuated closing plate 20 may alsocomprise an active compensator 27 in order to reduce the disturbance onthe liquid confinement structure caused, for example, when the liquidconfinement structure is removed from it. This compensator may comprisea vertical motion sensor and/or a pressure sensor on the actuatedclosing plate 20 and a control system configured to send a compensationsignal to, for example, a liquid confinement system positioner 29, theliquid confinement system positioner 29 configured to move the liquidconfinement structure 12 in response to the signal to compensate for thechange in force.

The substrate table WT and the actuated closing plate 20 are releasablycoupleable. This means that they may be attached together when theactuated closing plate 20 is replacing the substrate table WT and viceversa; but they can be detached from each other once the replacement iscomplete. The actuated closing plate 20 and substrate table WT maysimilarly be controlled by the same system 25 or 27 or by separatesystems 25 and 27. Separate long stroke actuators 22 a and 22 b as shownin the Figures may be used; but the separate actuators may be controlledby the same 25 or 27 or different control systems 25 and 27.

In an embodiment, forces on the actuated closing plate 20 may bemeasured, for example, by the actuated closing plate active compensator27 and fed-forward to a control system (e.g., active compensator 25) ofthe substrate table WT so that the forces acting on the actuated closingplate 20 will be compensated for and thereby not affect the substratetable WT. In this way, the actuated closing plate 20 may work as a forcemeasurement system for the substrate table WT.

While one or more embodiments may have been discussed in relation toremoving a substrate from the substrate table and placing anothersubstrate on the substrate table, one or more embodiments herein may beused in other applications. For example, the substrate may be kept onthe substrate table but the closing plate is used simply to close theliquid confinement structure. Further, while one or more embodiments mayhave been discussed in terms of the substrate acting as the boundary ofthe space between the projection system and the substrate, the substratetable may independently or conjunction with the substrate form a part ofthe boundary of the space. For example, a portion of the substrate table(e.g., an alignment mark) may be positioned under the liquid confinementstructure and form a part of the boundary of the space. Accordingly, theclosing plate may replace the substrate table as a part of the boundaryof the space, or vice versa.

In European Patent Application No. 03257072.3, the idea of a twin ordual stage immersion lithography apparatus is disclosed. Such anapparatus is provided with two tables for supporting a substrate.Leveling measurements are carried out with a table at a first position,without immersion liquid, and exposure is carried out with a table at asecond position, where immersion liquid is present. Alternatively, theapparatus has only one table

Although specific reference may be made in this text to the use oflithographic apparatus in the manufacture of ICs, it should beunderstood that the lithographic apparatus described herein may haveother applications, such as the manufacture of integrated opticalsystems, guidance and detection patterns for magnetic domain memories,flat-panel displays, liquid-crystal displays (LCDs), thin-film magneticheads, etc. The skilled artisan will appreciate that, in the context ofsuch alternative applications, any use of the terms “wafer” or “die”herein may be considered as synonymous with the more general terms“substrate” or “target portion”, respectively. The substrate referred toherein may be processed, before or after exposure, in for example atrack (a tool that typically applies a layer of resist to a substrateand develops the exposed resist), a metrology tool and/or an inspectiontool. Where applicable, the disclosure herein may be applied to such andother substrate processing tools. Further, the substrate may beprocessed more than once, for example in order to create a multi-layerIC, so that the term substrate used herein may also refer to a substratethat already contains multiple processed layers.

The terms “radiation” and “beam” used herein encompass all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.having a wavelength of or about 365, 248, 193, 157 or 126 nm).

The term “lens”, where the context allows, may refer to any one orcombination of various types of optical components, including refractiveand reflective optical components.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. For example, the invention may take the form of acomputer program containing one or more sequences of machine-readableinstructions describing a method as disclosed above, or a data storagemedium (e.g. semiconductor memory, magnetic or optical disk) having sucha computer program stored therein.

One or more embodiments of the present invention may be applied to anyimmersion lithography apparatus, in particular, but not exclusively, tothose types mentioned above. A liquid supply system as contemplatedherein should be broadly construed. In certain embodiments, it may be amechanism or combination of structures that provides a liquid to a spacebetween the projection system and the substrate and/or substrate table.It may comprise a combination of one or more structures, one or moreliquid inlets, one or more gas inlets, one or more gas outlets, and/orone or more liquid outlets that provide liquid to the space. In anembodiment, a surface of the space may be a portion of the substrateand/or substrate table, or a surface of the space may completely cover asurface of the substrate and/or substrate table, or the space mayenvelop the substrate and/or substrate table. The liquid supply systemmay optionally further include one or more elements to control theposition, quantity, quality, shape, flow rate or any other features ofthe liquid.

The descriptions above are intended to be illustrative, not limiting.Thus, it will be apparent to one skilled in the art that modificationsmay be made to the invention as described without departing from thescope of the claims set out below.

1. A lithographic projection apparatus, comprising: a substrate tableconfigured to hold a substrate; a projection system configured toproject a patterned beam of radiation onto the substrate; a liquidconfinement structure configured to confine a liquid in a space betweenthe projection system and the substrate, the substrate, the substratetable, or both, configured to form a part of a boundary of the space;and a closing plate configured to form a part of a boundary of the spacein place of the substrate, the substrate table, or both, when movedwithout substantially disturbing the liquid, the liquid confinementstructure, or both.
 2. The apparatus according to claim 1, comprising anactuator configured to move the closing plate along a horizontal planeto form the part of the boundary of the space in place of the substrate,the substrate table, or both.
 3. The apparatus according to claim 1,comprising an actuator configured to move the closing plate in a sameplane as the substrate, the substrate table, or both, and to follow thesubstrate, the substrate table, or both, across the liquid confinementstructure.
 4. The apparatus according to claim 1, wherein the substratetable comprises an active compensator configured to compensate for achange in load on the substrate table in a direction perpendicular to adirection of movement of the substrate table due to the replacement ofthe substrate, the substrate table, or both, with the closing plate as apart of the boundary of the space.
 5. The apparatus according to claim4, wherein the closing plate comprises an active compensator configuredto compensate for a change in load on the liquid confinement structurein a direction perpendicular to a direction of movement of the substratetable due to replacement of the closing plate with the substrate, thesubstrate table, or both, as a part of the boundary of the space.
 6. Theapparatus according to claim 1, wherein the substrate table and theclosing plate are releasably coupleable.
 7. The apparatus according toclaim 1, comprising a first actuator configured to move the closingplate and a separate second actuator configured to move the substratetable.
 8. The apparatus according to claim 1, wherein the closing plateis at a same vertical level as the substrate table and neither theclosing plate nor the substrate table is moved out of the vertical levelto replace the substrate, the substrate table, or both, with the closingplate as a part of the boundary of the space, to replace the closingplate with the substrate, the substrate table, or both as a part of theboundary of the space, or both.
 9. The apparatus according to claim 1,wherein the liquid supply system is configured to constantly circulatethe liquid in a flow pattern and the flow pattern is not disturbed bythe replacement of the closing plate with the substrate, the substratetable, or both as a part of the boundary of the space, replacement ofthe substrate, the substrate table, or both with the closing plate as apart of the boundary of the space, or both.
 10. A device manufacturingmethod, comprising: providing a liquid to a space through which apatterned beam passes, a substrate, a substrate table, or both, forminga part of a boundary of the space; sealing the liquid to the space, theseal acting between the substrate, a substrate table, or both, andanother structure; replacing the substrate, the substrate table, orboth, with a closing plate as the part of the boundary of the spacewithout breaking the seal; and projecting a patterned beam of radiationthrough the liquid onto the substrate.
 11. The method according to claim10, comprising moving the closing plate along a horizontal plane to formthe part of the boundary of the space in place of the substrate, thesubstrate table, or both.
 12. The method according to claim 10,comprising moving the closing plate in a same plane as the substrate,the substrate table, or both, and to follow the substrate, the substratetable, or both.
 13. The method according to claim 10, comprisingcompensating for a change in load on the substrate table in a directionperpendicular to a direction of movement of the substrate table due tothe replacement of the substrate, the substrate table, or both, with theclosing plate as a part of the boundary of the space.
 14. The methodaccording to claim 10, comprising compensating for a change in load on aliquid confinement structure, used to at least partly confine the liquidin the space, in a direction perpendicular to a direction of movement ofthe substrate table due to replacement of the closing plate with thesubstrate, the substrate table, or both, as a part of the boundary ofthe space.
 15. The method according to claim 10, comprising releasablycoupling the substrate table and the closing plate.
 16. The methodaccording to claim 10, comprising separately moving the closing plateand the substrate table.
 17. The method according to claim 10, whereinthe closing plate is at a same vertical level as the substrate table andneither the closing plate nor the substrate table is moved out of thevertical level to replace the substrate, the substrate table, or both,with the closing plate as a part of the boundary of the space, toreplace the closing plate with the substrate, the substrate table, orboth as a part of the boundary of the space, or both.
 18. The methodaccording to claim 10, wherein the liquid is constantly circulated in aflow pattern and the flow pattern is not disturbed by the replacement ofthe closing plate with the substrate, the substrate table, or both as apart of the boundary of the space, replacement of the substrate, thesubstrate table, or both with the closing plate as a part of theboundary of the space, or both.
 19. A lithographic projection apparatus,comprising: a substrate table configured to hold a substrate; aprojection system configured to project a patterned beam of radiationonto the substrate; a liquid confinement structure configured to confinea liquid in a space between the projection system and the substrate, thesubstrate, the substrate table, or both, configured to form a part of aboundary of the space; a closing plate displaced in a horizontal planefrom the substrate table and configured to form a part of a boundary ofthe space in place of the substrate, the substrate table, or both; andan actuator configured to move the closing plate in the horizontalplane.
 20. The apparatus according to claim 19, wherein the actuator isconfigured to move the closing plate in a same plane as the substrate,the substrate table, or both, and to follow the substrate, the substratetable, or both, across the liquid confinement structure.
 21. Theapparatus according to claim 19, wherein the substrate table comprisesan active compensator configured to compensate for a change in load onthe substrate table in a direction perpendicular to a direction ofmovement of the substrate table due to the replacement of the substrate,the substrate table, or both, with the closing plate as a part of theboundary of the space.
 22. The apparatus according to claim 19, whereinthe closing plate comprises an active compensator configured tocompensate for a change in load on the liquid confinement structure in adirection perpendicular to a direction of movement of the substratetable due to replacement of the closing plate with the substrate, thesubstrate table, or both, as a part of the boundary of the space. 23.The apparatus according to claim 19, wherein the substrate table and theclosing plate are releasably coupleable.
 24. The apparatus according toclaim 19, comprising a separate actuator configured to move thesubstrate table.
 25. The apparatus according to claim 24, comprising acontroller configured to separately control the closing plate and thesubstrate table.
 26. The apparatus according to claim 19, wherein theactuator is configured to move both the closing plate and the substratetable.
 27. The apparatus according to claim 19, wherein the closingplate is at a same vertical level as the substrate table and neither theclosing plate nor the substrate table is moved out of the vertical levelto replace the substrate, the substrate table, or both, with the closingplate as a part of the boundary of the space, to replace the closingplate with the substrate, the substrate table, or both as a part of theboundary of the space, or both.
 28. The apparatus according to claim 19,wherein the actuator comprises a long stroke actuator and comprises along stroke actuator configured to move the substrate table.
 29. Theapparatus according to claim 19, wherein the liquid supply system isconfigured to constantly circulate the liquid in a flow pattern and theflow pattern is not disturbed by the replacement of the closing platewith the substrate, the substrate table, or both as a part of theboundary of the space, replacement of the substrate, the substratetable, or both with the closing plate as a part of the boundary of thespace, or both.